1. Field of the Invention
The present invention relates to a car navigation system.
2. Description of the Related Art
A car navigation apparatus has been developed that quickly and safely guides a driver to a destination and provides the driver with desired facility information and region information as additional information. The car navigation apparatus calculates a path to guide a car to the driver's destination and provides the driver with drive instructions with considering the car's current location and driving direction so as to make the car drive along the calculated path.
The above-mentioned car navigation apparatus provides a navigation function, a path calculation function, a map display function, a path guide function and a facility information function.
The navigation function is a function to frequently obtain the location of the car and inform the driver of the location when a car runs. To implement this navigation function, required are a GPS receiver, a speedometer and a gyro sensor. The speedometer informs the driver of a current location using a relative location according to movement of the car.
The map display function is a function to display roads, surrounding facilities and background so as to allow the driver to watch a displayed map and recognize his or her location. The map display function should provide a function to magnify or contract a map and quickly shift screen in eight directions of north, south, east, west, northeast, northwest, southeast and southwest.
The path calculation function is a function to find optimal path to a desired destination. The path guide function is a function to guide the driver according to an optimal path obtained from path calculation. In other words, the car navigation teaches the driver which road to go along, underground road or elevated road, and teaches the driver which direction to turn at an intersection. Also, when the car approaches an intersection, the car navigation displays a magnified map of the intersection to help the driver driving the car along exacter path. The facility information function is a function to provide the driver with information on a desired facility, for example, location of and related information on a specific facility nearest to the current driver's location. To implement this function, required is information on various facilities.
The car navigation apparatus performing such functions has map information deliberately and updates the map information in real time or by off-line. In other words, the car navigation apparatus updates the stored map information in real time through wire or wireless communication network or receives the map information from a service provider by off-line to update.
The related art method for updating the map information at the car navigation apparatus will be described in detail referring to accompanying drawings.
FIG. 1 shows a related art car navigation apparatus for updating the map information.
The related art car navigation apparatus for updating the map information includes a display unit 100, a first memory means 110 and a reproduction unit 120 as shown in FIG. 1. The display unit 100 outputs road map information. The first memory means 110 stores road map. The reproduction unit 120 reproduces road map data of the first memory means 110.
In addition, the related art car navigation apparatus further includes a car location detection sensor 130, an input unit 140 and a controller 150. The car location detection sensor 130 detects a location of a car. The input unit 140 receives a user control signal by user's manipulation. The controller 150 controls the reproduction unit 120 according to a control signal inputted from the input unit 140. Herein, the controller 150 reproduces road map data of the first memory means 110 and controls the display unit 100 to display the reproduced road map data, and also, at the same time, controls the display unit 100 to display a location of a car according to a location signal inputted from the car location detection sensor 130.
The related art car navigation apparatus further includes a receiver 160 and a second memory means 170. The receiver 160 receives road map data transmitted from a base station. The second memory means 170 can store, read and write updated road map data.
The method for updating the map information at the related art car navigation apparatus described above will be described. If the road map data received through the receiver 160 is different from the data stored in the second memory means 170, it is determined that the received road map data is new data and the newly received road map data is stored the second memory means 170. Then, the car location detection sensor 130 detects location of its car. Herein, if surrounding road map data of the location of the car is stored in the second memory means 170, it is determined that the data is updated, and then road map data is read from the second memory means 170. If the surrounding road map data of the location of the car is not stored in the second memory means 170, the road map data is read from the first memory means 110 and is outputted through the display unit 100. Accordingly, since the road map data outputted from the display unit 100 is updated and outputted whenever traffic situation is actually changed, a driver can drive safely and actual traffic situation is informed of to the driver regardless of a data update period of the first memory means 110.
According to the related art described above, however, since determination of whether the map data is updated and version management object depends on shape information of a map, an update history for the case that guidance information is changed cannot be managed.
In addition, since a map update contents management criterion is focused on map production, if the guidance information for actual guidance is changed in a car navigation apparatus, a proper response is impossible to make.
Additionally, if information is received and terminal map is updated in real time, since map update contents are generated by one time production for an entire map and the amount of updated information is enlarged, it is required to transmit a large amount of data.
In addition, in a payment system that a user is charged in unit of transmission packet, since a large amount of information is received including unnecessary information as well as a currently essential interested information, unnecessary cost is charged.
Additionally, in case that a large amount of information is updated, if the amount of the entire map exceeds an accommodating dynamic memory size, the information cannot stored.